Year	Measure
1990	0.676
1991	0.67
1992	0.663
1993	0.656
1994	0.652
1995	0.654
1996	0.665
1997	0.669
1998	0.672
1999	0.679
2000	0.686
2001	0.692
2002	0.694
2003	0.705
2004	0.719
2005	0.732
2006	0.754
2007	0.771
2008	0.782
2009	0.784
2010	0.78
2011	0.778
2012	0.773
2013	0.772
2014	0.773
2015	0.775